Case Study

Frac Tower Return to Service



Oil & Gas Infrastructure

Midstream, Retrofit, Debottleneck, Safety Review

The Challenge:

In 2015, a Midstream distribution company (“Client”), with terminals spanning across the United States, approached Halker
Consulting LLC (“Halker”) for help placing a fractionator back into service at one of their Texas terminals. Their goal was to improve
their ability to separate the diesel/gasoline transmix they received to increase profitability. Beyond process optimization to
maximize profits, the client wanted to evaluate the aging facility’s safety system. The project included a variety of aspects,
such as:
– Piping Design & Two-Phase Pipe Stress Analysis
– Equipment & Pipe Support Structural Design
– PLC Upgrade & Instrumentation Design
– ASME Section VIII Pressure Vessel Calculations
– Tray Study
– PSV & Relief Header Evaluation Sizing

The Design:

FACILITY DESIGN: The project necessitated a site walk-down where Halker created isometric drawings of the existing system to begin the piping design effort. After gaining a solid understanding of the existing layout Halker was able to model the preliminary piping design and simultaneously analyze the pipe stress in the two-phase flow system. This parallel workflow allowed a constant iteration process between design and analysis until the most efficient system was achieved.

PROCESS OPTIMIZATION: Following the successful design to place the fractionator back in service, the Client requested Halker to perform a process study of the fractionator to see if the tower was limiting the amount of product that could be processed. The study involved simulating and analyzing the tray design and layout within the tower and suggesting potential changes to
increase output. For this instance, Halker found that only marginal gains could be made by changing the tray design and, after
discussion with the Client the modifications were determined to be uneconomical. The client was not only focusing on optimizing existing facilities to increase profitability, but they were also concerned with upgrading the safety system. Halker analyzed the existing system to define deficiencies and determine the most efficient path forward while maintaining the safety of the operators working in the facility. After brainstorming numerous possibilities to reduce costs, it was decided that additional relief valves had to be installed. Halker recommended the locations, sizes and
routing for the additional relief valves.

The Result:

Through a multi-disciplinary effort that included process, mechanical, electrical, instrumentation and structural engineering, in addition to piping design, the client was able to successfully place the fractionator back in service. With the additional tower in operation the capacity of the plant was no longer limited by separation, allowing for potential low cost upgrades for future plant expansion. Additionally, with the renewed look at the safety system, the client can be assured that their facility is adequately protected from a variety of potential over pressurization events.